1. Field of the Invention
The present invention relates to an optical connector ferrule that allows multiple optical fibers to be coupled precisely when connecting or switching operation is performed on lightwave communication systems.
2. Prior Art
FIGS. 1A and 1B are schematic drawings of a prior art (5-count) optical connector ferrule, in which FIG. 1A is a top view and FIG. 1B is a front view of the coupling end of the connector shown in FIG. 1A.
As shown in the figures, two guide pin holes 31 are formed in a resin-molded member 30. The optical fibers (B) in a multi-fiber array (A) are aligned on the line connecting the centers of the axes of the guide pin holes 31 and are coupled to the optical fibers in another connector by inserting two guide pins 32 into the corresponding guide pin holes 31 in each connector. The guide pins 31 are spaced from each other at a pitch of 3,600 mm and the optical fibers (B) are spaced at a pitch of 0.250 mm.
The above-described prior art optical connector ferrules require two guide pins for achieving their coupling and they cannot be handled as conveniently as electrical connectors which can be coupled by simply inserting plugs into a common adapter. In order to couple the conventional optical connector ferrules, careful and cautious procedures must be followed using guide pins. A further problem arises from the fact that there is no consistency in the presence of guide pins in the optical connector ferrules after they are dismounted, and every time they are to be reconnected, the operator must check to see if they retain guide pins and, if not, the necessary guide pins are furnished. This problem may be solved by permanently embedding guide pins in several optical connector ferrules but this idea has not been commercialized since it involves many disadvantages associated with practical applications, such as the incapability of coupling two connector ferrules both having permanently fixed guide pins. The difficulty involved in handling guide pins is further increased by the fact that they have a very small diameter 0.7 mm.
Further, the guide pin holes which are formed by resin molding are prone to wear or be damaged when guide pins are inserted into these holes, and great difficulty is encountered in realizing high-precision and reliable coupling of optical fibers.
It becomes more difficult to achieve precise coupling, and keeping the amount of offsetting to be within 1-2 .mu.m involves extreme difficulty in view of production efficiency, as the number of optical fibers to be connected increases since the multiple fibers are molded in one operation. The optical fiber guide holes are also formed with molding pins placed in alignment in the mold and this increases the change of the molding pins being deformed either under the molding pressure or during their setting in the mold.